Government agencies are applying exhaust emission control regulations to protect the environment. These regulations are being applied to combustion engines including portable or two cycle engines used in equipment such as chain saws, lawn mowers and hedge trimmers, as well as four cycle engines. One means of limiting excessive exhaust emissions in a combustion engine is to restrict the maximum amount of fuel delivered to the engine combustion chamber. This maximum fuel amount is pre-set on each individual engine by the engine manufacturer with the understanding that the end user requires some adjustment capability to meet changing work conditions and environmental factors such as altitude, dirty air filter, and different fuel. Not only is it desirable to limit the richness of the fuel to air mixture because of exhaust emission regulatory concerns, but the engine manufacturer may also want to restrict minimum amounts of fuel, or the leanness of the fuel to air mixture. For example, a user desiring more power from a two cycle engine may attempt to operate the engine in an ultra-lean state. This may affect desired cooling of the engine.